Making optical cables out of air could boost communication in space

Under our feet, cables carry data between our homes, offices and data centers at a pace that can match the speed of light. The data travels as light that runs through strings made of materials like glass and plastic.

Researchers at the University of Maryland want to do away with the cable altogether and just use air to guide the light. That’s not as simple as it sounds, because a laser sent through air will spread apart and interact with particles, gradually losing its intensity over time.

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The research team instead caused patches of air to mimic a fiber optic cable by creating tubes of dense air surrounded by low-density air. In a fiber optic cable, a laser travels through a string of glass. When it tries to leave the glass, it hits a wall that reflects it back into the center, guiding it along the length of the cable. The cable made of air works in the same way.

“It’s like you could just take a physical optical fiber and unreel it at the speed of light, put it next to this thing that you want to measure remotely, and then have the signal come all the way back to where you are,” University of Maryland team lead Howard Milchberg said in a release.

To create the air cable, the team sent short pulses of a high-power laser, which causes particles in the air to collapse into a dense string. The air around it expands, leaving a low-density tube around the core. While the cable only lasts for a few milliseconds, that is a million times longer than the pulse it takes to create it. And Milchberg said for many uses for laser communications, “milliseconds is infinity.”

Signals that traveled through the air cable were 1.5 times stronger than when they were sent through plain air. The team was able to send them over a distance of three feet and is now interested in pushing the range to 150 feet.

If the University of Maryland team succeeds, the air cables could be used for communication in remote locations on Earth where laying fiber optic cables is extremely difficult, or places where it actually is impossible like space. NASA is already experimenting with laser communication between the International Space Station and Earth. The technique could also be used to probe the Earth to make topographic maps or examine the chemicals present in hard-to-reach places like the atmosphere or a nuclear plant.

Hi Signe.
I don’t know if you are aware of it but this article has been used in an English test for a very big public job selection in Brazil. There are some interpretations that were made by the examiner about your text and I would like to confirm them with you. Would it be correct to state that NASA is testing the same technology that is being developed at the University of Maryland? Will this new technology enable signals to be sent to longer distances than the regular cable system? Thanks in advance!

Interesting! I had no idea. Are you referring to OPALS at NASA? I don’t think they are the same, though they are both light-based.

The distance currently achievable is much shorter than you can do with cables. It could allow data to reach areas cables never could, such as space. I’m not sure of the maximum distance the air-based optical cable could reach, sorry. Here is the original research paper:

Great post. It might not happen tomorrow, but it certainly seems possible. It is amazing what people can come up with when they are hindered by preconceived limitations. Before the space station was established, many people would say it was unlikely. Thankfully, there are people with a combination of imagination and skill. This is exciting news.

One of the first pieces of glass used in space was created by the Schott Glass Company. Maybe the University of Maryland should partner with the Schott Glass Company to develop this idea?

This article is very speculative, and does not accurately represent the research cited. The applications of said research are in the field of high-energy lasers, not laser communication, and therefore have little crossover with the field of fiber optic communications.